BRITISH GEDLOGICAL SURNEY

!llZC!EiNICAL REPORT WA/97/77 Onshore Geology Series

'JXC!EiNICAL REPORT WA/97/77 Geological notes and local details for 1:lO 000 sheet TG 22 NE (Westwick) Part of 1:50 000 sheets 147 (Aylsham) and 148 () R J 0 Hamblin

Geographical index UK, E , E Anglia,

Subject index Geology, Quaternary, Cretaceous

Bibliographic reference Hamblin, R J 0. 1997. Geological notes and local details for 1:lO 000 sheet TG 22 NE (Westwick). British Geological Survey Technical Reprt WA/97/77.

@ NERC copyright 1997 Keyworth, Nottingham. British Geological Survey 1997. The full range of Survey publications is available Parent Body through the Sales Desks at Keyworth and at Murchison House, Edinburgh, and in the BGS Natural Environment Research Council London Information Office in the Natural History Polaris House, North Star Avenue, Swindon, Museum Earth Galleries. The adjacent bookshop Wiltshire SN2 IEU. stocks the more popular books for sale over the Telephone 01793 411500 counter. Most BGS books and reports are listed in Telex 444293 ENVRE G HMSO’s Sectional List 45, and can be bought FUX 01793 411501 from HMSO and through HMSO agents and retailers. Maps are listed in the BGS Map Catalogue, and can be bought from Ordnance Kingsley Dunham Centre Survey agents as well as from BGS. Keyworth, Nottingham NG12 5GG. Telephone 0115 936 3100 The British Geological Survq carries out the Telex 378 I73 BGSKEY G geological survey of Great Britain and Northern FUX 0115 936 3200 Ireland (the latter as an agency service for the government of Northern Ireland), and of the Murchison House, West Mains Road, Edinburgh surrounding continental she& as well as its basic EH9 3LA. research projects. It also undertakes programmes Telephone 0131 667 I000 of British technical aid in geology in developing Telex 727343 SEISED C countries as arranged by the Overseas FUX 01 3 1 668 2683 Development Administration. London Information Office at the Natural The British Geological Survey is a component History Museum, Earth Galleries, Exhibition body of the Natural Environment Research Road, South Kensington, London SW7 2DE. Council. Telephone 0171 589 4090 Telephone 0171 938 9056157 FUX 0171 584 8270

19 Grange Terrace, Edinburgh EH9 2LF. Telephone 0131 667 1000 Telex 727343 SEISEDc

St Just, 30 Pennsylvania Road, Exeter EX4 6BX. Telephone 01392 78312 FUX 01392 437505

Geological Survey of Northern Ireland, 20 College Gardens, Belfast BT9 6BS. Telephone 01232 666595 FaU 01232 662835

Maclean Building, Crowmarsh Gifford, Wallingford, Oxfordshire OX 10 8BB. Telephone 01491 38800 Telex 849365 11YDROI. G FaU 01491 25338 Technical Report WA/97/77 17th September 1997

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MADE GROUND, MORKED GROUND AND LANDSCAPED GROUND 26

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1 Technical Report WA/97/77 17th September 1997 GED~CALNCFIESANDLOCALDETAIISFOR~~CALS~ 'Iy: 22 NE 0;vEsnVrcrq

The following report is designed to be used in conjunction with 1 : 10 000 Geological Sheet TG 22 NE. Uncoloured copies of the map may be purchased fiom the Survey's offices at Keyworth. The district covered by the map is included in 1 : 50 000 Geological Sheets 147 (Aylsham) and 148 (North Walsh). It formed part of Old Series One-Inch sheet 68E, and was surveyed at a scale of 1 : 63 360 by H B Woodward in 1879. An accompanying memoir was published (Reid, 1882). The district was resurveyed at 1 : 10 000 scale by the present author in 1996-7, with Dr I R Bashas regional geologist. The area lies to the north of (Figure 1). The market town of North Walsham extends onto the northern part of the sheet, and into the south-eastern corner. Apart fiom this the area is predominantly rural, with the small settlements of Westwick, and in the south. In the north of the area the land rises to a plateau, with maximum altitudes of over 40m OD at Lord Anson's Wood [26 281 and North Walsham [28 291. Small streams drain this plateau to the west, south and east, including Skeyton Beck in the north- west and Stakebridge and Westwick becks in the south. All are tributaries of the River Bure, which flows into the area known as the Norfolk Broads and ultimately drains to the sea at Great Ymouh.In the east the ground drops away rapidly into the valley of the River Ant, a major tributary of the Bure.

In general the high plateau formed by the sands of the Corton Formation, which is very well drained, forms poor agricultural land and is traditionally grazed by sheep, hence the importance in medieval times of cloth manufxture in the village of Worstead. Nowadays much of this higher land is given over to commercial woodland and pheasant rearing. The remainder is wed for arable crops but requires intensive irrigation. However, some areas of the Corton Formation outcrop, particularly at lower levels, are covered by up to rather more than a metre of cover silt, and these areas, along with the outcrop of the Crag Group, produce excellent agricultural land, neither too heavy nor too light. Large crops of wheat, barley, sugar beet and potatoes are grown, and owing to the water-retentive properties of the cover silt, little artificial irrigation is required despite the low rainfall in this part of the country. The alluvium and peat outcrops of the Stakebridge Beck and Westwick Beck are given over to woodland and permanent pasture, grazed by cattle, sheep and horses. National Grid References in this report are given in square brackets; these all fall within 100- kilometre square TG. All depths and thicknesses in the report are given in metres. The non- confidential water wells and boreholes in the district are shown on Figure 2; identification numbers quoted are those of the BGS records collection, in which they are prefixed TG 22 NE. Complete logs of the non-confidential wells and boreholes can be obtained fiom BGS Information Services (Geological Records) at Keyworth.

rc F

2 Technical Report WA/97/77 17th September 1997

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8 Water well(s) or bore@) Water well or bore, no geological log known Water well(s) or bore@), site uncertain

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4 Technical Report WA/97/77 17th September 1997 GEoIxxacAL SEQUIENCE

Strata proved on sheet TG 22 NE are listed below. BGS practice in East Anglia is to classifL all deposits overlying the Crag Group as Drift, and the Crag Group as the youngest deposit of the solid succession.

Hblocene to Recent Weground Up to c 5.0 Peait upto c 2.0 Alluvium up to c 2.0 Pleistocene to Recent €lead up to c 2.0 Pleistocene aver silt Up to c 1.5 we1and sand Up to c 3.0 Yrue Valley Foimation up to c 2.0 Carton Foimation Up to c 35.0 CwJmUp Up to c 25.0 uncOnfownity Upper ctetaceous UpperGhalk 96-t

4

5 Technical Report WA/97/77 17th September 1997 som lKNmTAnms

No strata older than the Upper Chalk have been proved by boreholes within the district, but deep boreholes in the surrounding area (Figure 3) have penetrated strata as old as Silurian. Details can be obtained fiom the BGS Records Collection, and are summarised in Arthurton et al. (1994). All three subdivisions of the Chalk Group, the Lower, Middle and Upper Chalk, are present beneath the whole of the district, although only the Upper Chalk has been proved in boreholes. The biostratigraphy, lithology and structure of the Chalk of Norfolk have been reviewed by Peake and Hancock (1961, revised and re-published 1970). The lithostratigraphy, biostratigraphy and history of research of the Chalk of Norwich were updated by Wood (1988), which is summarised in the memoir for the district (Cox et al., 1989). A map of sub-divisions of the Chalk at rockhead (Peake and Hancock, 1970) indicates that the district is largely underlain by Parmoudra Chalk, with Maastrichtian Chalk coming in at depth beneath the Crag in the east (Figure 3). Levels of the base of the Group are also given on Figure 3: these imply a level of around -450m OD beneath the present district. Since the base of the Crag here lies at around +1Om OD, this implies that the thickness of the Chalk Group is about 460m. The base of the group is believed to dip regionally to the north-east at 0.25" to 0.5" (Arthurton et al., 1994). On sheet TG 22 NE the Upper Chalk has been penetrated by 30 boreholes. Thicknesses of Chalk penetrated are shown on Figure 4; the maximum is 95.6m at borehole TG 22 W17 [278 2911.

The principal lithology of the Chalk Group is so& white, micritic, coccolith limestone, generally rather porous and poorly cemented. The Lower Chalk is less pure than the Middle and Upper Chalk and is grey in colour and flintless, with some indurated layers or 'hardgrounds', and bands of dark grey shell-detrital chalk. The Middle Chalk is flintless except for two horizons, and includes seams of mar1 throughout its thickness and beds of shell- detrital chalk in its lower part. The bulk of the Chalk Group however comprises the Upper Chalk, which is notably white, and rich in flint in the form of nodules or in tabular form. It contains a number of hardgrounds.

The Tmch Borehole (Gallois and Morter, 1976) (Figure 3) was sunk to provide a standard sequence for the Upper Cretaceous of East Anglia. The fbll log is held in the BGS Records Collection, while the biostratigraphical zones recognised are summarised in Table 2 (after Arthurton et al., 1994). Comparing this with the subdivisions used by Peake and Hancock (1970) (Figure 3), the B. lmeolata zone corresponds with the Mmstrichtian, while the Paramoudra Chalk, Beeston Chalk, Weybourne Chalk, Eaton Chalk and Basal mzicmnata Chalk are all B. mucmnata zone, and the 0. pilula zone is included in Peake and Hancock's map along with the G. qddazone.

6 Technical Report WA/97/77 17th September 1997 The lithologies of the main subdivisions of the Upper Chalk in the Tmch Borehole may be summarised as follows:

Thickness

Maastrichtian Chalk: SORmarly chalk with large flints; low core recovery c 21.3 Paramoudra Chalk: massive white chalk with large tabular thalassinoid flints, generally few fossils c 54.5 Beeston Chalk: yellow, white and grey, fossiliferous chalks with large thalassinoid flints; hardgrounds at the top and base of the unit, the latter equivalent to the Catton Sponge Bed of Norwich c 31.1 Weybourne Chalk and Eaton Chalk: grey-white marly and hard yellowish chalks with large thalassinoid-nodular flints; very fossiliferous c 39.4 Basal mucmnata Chalk: grey-white chalk with more marly bands and large and small nodular flints; tough hardground marking base of zone c 17.0 Gonioteuthis quardrata Zone: grey-white marly chalk with large nodular flints; creamy white chalk with small nodular and lensoid flints c 63.47 qfmter pilula Zone: massive white chalk with a few tabular flints 34.25 Mmupites testudinun-m and Untmim socidis mnes: white massive chalk with oyster beds; largely flintless except for occasional thin tabulars 28.84 Mimter comguinum Zone: hard grey-white marly burrowed chalk, with small scattered nodular flints; bands of medium-sized nodular flints and Imceramm shells below 84.7 Micrmter cortestudinuniwn Zone: hard grey-white and yellowish white chalk, with stylolitic surface, thin marl seams, hardgrounds and medium-sized nodular and tabular flints; fossiliferous, several sponge beds 11.77 Stemtmisplmm Zone: hard white massive chalk with several major hardgrounds, marly concentrations and sponge beds stained yellow or grey; flints small and nodular or thin and tabular; conspicuous marl seam at base of Upper Chalk 30.71 Technical Report WA/97/77 17th September 1997

TF 00 10 20 30 40 50 TG

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8 Technical Report WA/97/77 17th September 1997

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-3 -2 27. IL 9

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‘includes an unnamed zone, the Myrilorde.~spp Zone and the Neocardioceras juddir Zone

10 Technical Report WA/9 7/77 17th September 1997 THE UPPER SURKACE OF THE UPPER CHALK

Figure 4 shows the levels of the surface of the top of the Upper Chalk, in all cases overlain by the Crag Group. Allowing for the inevitable errors in borehole logging, this indicates a gently undulating swfke, lowest (-lOm OD) in the south-east and highest (+5 OD) in the south-west.

The upper surface of the Upper Chalk is commonly weathered to a soft, weak material sometimes known in borehole logs as 'putty chalk'. The term mar1 is also common in borehole logs and is also taken to imply soft chalk. In the Tmch Borehole, Gallois and Morter (1976) recorded poor core recovery in the highest 34m of the Upper Chalk, although here it was possibly glacially disturbed. In percussion-drilled water wells, the top of the Chalk may not always be accurately recorded because of this softening; sand fiom higher strata may fall down the hole, mixing with the soft chalk and staining it brown. In the district to the south (TG 22 SE; Hamblin, 1997a), the levels of the top of the Upper Chalk in boreholes are consistently a few metres lower than the levels mapped along the sides of the valleys of the Bure and its tributaries, suggesting a consistent error on the part of the well-sinkers, which is most likely a reflection of the weathered state of the top part of the chalk. However, borehole logs suggest that there is much less weathering of the Chalk surface on both sheets TG 22 SE and TG 22 NE than in the Belaugh district (TG 21 NE; Hamblin, 1997b), presumably because the Upper Chalk lies at a much shallower depth in the latter district. In the present district, softening of the upper surface of the Upper Chalk is indicated by 'ml' in boreholes TG 22 NU8 [255 2581, /11 [282 2941 and /21 [2551 25601, 'loose chalk' in /8, 'clay and chalk' in TG 22 W14 [2840 28001, and 'soft chalk' in /14 and /26 [2700 25381. Borehole TG 22 W1[2785 28341 refers to 'brown sand and chalk' at the top of the Upper Chalk, implying that the sand has caved into the chalk during drilling: /18 [278 2911 refers to 'duty chalk', which may also be an artifact of percussion drilling. Technical Report WA/97/77 17th September 1997 QUA'IXRNAFlY - CRAG GROUP The Crag Group represents the relatively coarse-grained marginal facies of a well-developed clastic sequence present in the southern North Sea (Cmeron et al., 1992). The strata comprise sands and shelly sands with subordinate seams of clay and gravel. Flints form the bulk of the clasts in the gravels, although quartz and quartzite become important in gavels in the higher part of the sequence. The bulk of the sediments are fme- to medim-grained well-sorted mica~eoussands. In an unweathered state they are glauconitic and dark green or dark grey in colour, but near the surface they become oxidised to shades of yellow and red, with layers of iron pan developed fiom the decomposition of glauconite. Fossils are not common, and it has been suggested that the Crag has become decalcified, at least in its upper part. The Red and Norwich Crag formations of Suffolk have recently been described by Hamblin et al. (1997). They record a series of transgressions and regressions (Figure 5), and have placed the base of the Norwich Crag at the unconforrnity shown at the base of the Antidrmertonian strata. In eastern Norfolk, both the Red and Norwich Crag formations are know with the latter transgressing the former to rest upon the Upper Chalk near Norwich (Funnel1 et al., 1979). However, it is now clear that the uppermost Crags of Norfolk, including the so-called Weybourne Crag and Bure Valley Beds (Hamblin, 1997% b), are significantly younger than any known in Suffolk. Current Survey practice is to include all these marine and estuarine deposits which infill the Crag Basin within the Crag Group, although on this basis the Crag Group includes deposits of Pastonian age which would be included in the Forest-Bed Formation by West (1980).

The uppermost Crag in the present district belongs to the Bure Valley Beds, although borehole and surface mapping evidence implies that they are less gravelly than in the type area of the Bure Valley around . The Bure Valley Beds have been shown on the 1: 10 000 scale maps as Norwich Crag Formation, but at the time of writing it is proposed to raise the term Wroxham Crag Formation to include the Bure Valley Beds, the Weybourne Crag, and certain other similar deposits of Pastonian and Pre-Pastonian age. The Wroxham Crag differs fiom the underlying Norwich Crag in that its gravel component is characterised by a significant proportion of quartz and quartzite as well as flints. The Wroxham Crag is known to overstep the Norwich Crag, resting directly upon the Upper Chalk in the Belaugh district (TG 21 NE, Hamblin 199%). It is possible that the Norwich Crag is also present at depth in the Westwick district, while the Red Crag is assumed to be absent.

The sands of the Crag Group are fine- to medium-grained, well-sorted and micaceous. In an unweathered state they are glauconitic and dark green or dark grey in colour, but near the surface they normally become oxidised to shades of yellow and red, with layers of iron pan developed fiom the decomposition of glauconite. Both grey, green and brown sands are mentioned in borehole logs, indicating that unweathered glauconitic strata are preserved at depth. Fossils are not common, especially in the upper part of the sequence, possibly as a result of decalcification, but shelly sands are common lower in the sequence; shells are recorded in boreholes TG 22 W2to 4, 15, 17, 18,26 and 28 to 30. c Gravels are an important constitu&t of the local Crag: only boreholes TG 22 W2, 5 to 8,

12 Technical Report WA/97/77 17th September 1997 12 and 28 to 30 record complete sequences with no mention of gravel at all, either as gravel, shingle, flints or stone. The thickest gravel bed mentioned in a borehole is 7.6m thick, at the base of the Crag in borehole TG 22 NI322 [2711 25521. The gravel is dominated by flint clasts, and these may be up to 20cm long. The flints are generally of high sphericity, well rounded and chatter marked, particularly the smaller ones, but in the Belaugh district (TG 21 NE, Hamblin 199%) a distinction was noted between pits in which massive beds of very high sphericity flints are believed to indicate beachface aggradation [2662 1680, 2872 17241, and a pit [2696 17001 with less massive, more sandy beds of gravel, with flints of lower sphericity, which is believed to indicate offshore, possibly sub-littoral sedimentation. However it is generally considered that the flints are second-cycle, derived fiom preexisting Palaeocene outcrops to the west (Moorlock et al., in press), so if the distinction noted here is correct, then the very high degree of rounding of the beachface-facies flints must be an effect of the Quaternary re-working. Quartz and quartzite are also important constituents of the gravels in the Wroxham Crag, but not in the Norwich Crag.

The Crag commonly has a basal bed of pebbles and cobbles of glauconitecoated flint, representing a transgressive beach deposit (Hamblin, in Moorlock et al., in press). This is generally refared to as the Stone Bed. It is present at the only pit at which the unconformity was observed during the present survey, in the Belaugh district [2657 16751 (Hamblin, 1997b). The flints there are up to 20 cm long, with black cortices and white patinas, with their horns broken off by abrasion, in a matrix of coarse-grained orange-brown sand. In the present district, boreholes TG 22 W1, 3,4, 11, 15, 17, 18, 21, 22, 23, and 27 specifically mention gravel at the base, in the form of gravel, shingle, flints or stones.

Clays, generally grey or buff in colour, are common in the Crag, interbedded with the sands and gravels. They are recorded (as 'clay' or 'marl') at all levels in the sequence in the present district, variously grey, yellow, brown and blue in colour, and in all boreholes recording complete sequences of Crag except TG 22 NE/4, 7, 11, 20, 21,27, 29 and 30. In eastern Suffolk a similar aggradation of sands, gravels and clays is recorded (Hamblin, in Moorlock et al., in press), and interpreted as a coastal complex, with gravel bodies (the 'Westleton Beds') interpreted as shoreface deposits, and the Easton Bavents and Covehithe clays interpreted as estuarine and lagoonal. The same interpretation may apply in the present district.

The levels of the base and top of the Crag Group, as logged at outcrop and in 30 boreholes which penetrated to the Upper Chalk, are shown on figure 6. As explained above, levels for the base are likely to be accurate to a metre or so. They vary fiom OD -1Om in the south-east to OD +5m in the south-west. At outcrop the boundary at the top of the Crag Group is comtnonly difficult to fur by augering because of a wash of gravel fiom the overlying Corton Formation, and there is rarely a clear change of slope at the boundary: it ranges fiom around +13 to +18m OD in the south of the district. In boreholes this boundary is even more dacult to fix, since both the Crag and the Corton Formation are characterised by sands, gravels and clays. It is known with reasonable confidence at +1 lm OD in borehole TG 22 W26near the outcrop, and at +10/13m OD in TG 22 W11 and /15-18 in North Walsham, and it is ass4to adopt a roughly planar surface fiom here to its outcrop. On this basis, it is possible to place the base with raker less confidence at boundaries recorded in boreholes

13 Technical Report WA/97/77 17th September 1997 TG 22 W1,3,4,7, 12, 14,20 and 28. However, at TG 22 NE/5,6 and 13 it appears to lie within a thick clay unit, and within thick sand and gravel units in 2, 23, 29 and 30. The greatest figure for the thickness of the Crag which can be given with confidence is thus 12.4m at borehole TG 22 W15, and a figure of c 12m has been adopted for the 1 : 10 000 scale map. However, if the estimates for the level of the top of the group in other boreholes are correct, then the greatest thickness is 23m in TG 22 W12 in the west.

Local details

Around Hall Farm [255 2521, gravels, sands and sandy clays were augered in the fields, and a pit [254 2511 may have been worked for either gravel or clay. Borehole TG 22 W21 [2551 25601 records sand and stone fkom 4.3m to 9.8m depth, beneath a brick-lined well, but borehole TG 22 NE/8 [255 2581 records yellow clay to 2.lm then brown and grey fine- grained sand resting upon the Upper Chalk at 11.6m depth.

East of Cramp Lane [258 2551, the Wroxham Crag crops out over a broad flat area. Pale grey and brown clays, grey medium-grained sands and orange fine-grained sands were auger4 but much of the area could not be penetrated with the auger owing to a wash of gravel. The farmer reports the fields here as heavy and difficult to work, and the uneven area either side of the filter beds [265 2511 may be abandoned clay workings, but where children have dug 'dens' hereabouts [263 2511 sand is revealed. Borehole TG 22 W27 [2670 25251 recorded sand and shingle layers to 11.6m depth, beneath an existing well 3.0m deep. North of here, orange sandy soil in the fields proved on augering to be very gravelly. East of Westwick Beck, the outcrop is largely covered with gravel to the north of Aylsham Road, but south of the road, orange and grey clays and orange come sands were augered, and orange sand was revealed in a badger sett [2683 25291. Several small pits [2730 2574, 2689 2545,2703 2544,2746 25151 may have been worked for gravel or clay. In the east of the Crag outcrop, augering distinguished fine- to come-grained orange sands of the Crag fiom the overlying fine-grained pale yellow sands of the Corton Formation.

14 Technical Reprt wA/97/77 17th September 1997

07 70 Baventian 0-T -.____ -. 0 5

Thurnian ox Lu d h amion 70 00- cc1

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15 Technical Report K4/97/77 17th September 1997

I -12 n +10/13 3 2 -3 0 +2 29

-1 1

0

P

I I I ( I-

6 7 3

16 Technical Report WA/97/77 17th September 1997 DIUFI'DlZPCBm

It is the practice of the British Geological Survey to portray the largely marine Early Quaternary deposits of the Crag Group as solid, and all succeeding deposits as 'drift'. In the present district the earliest drift deposits known to be exposed at surface are the Corton Formation, a glacigenic formation of Anglian age. However, it is possible that earlier, pre Anglian drifi deposits are represented at depth, or even that they appear at outcrop and have not been distinguished fiom the overlying Corton Formation.

In Suffolk, three pre-Anglian drift formations are known (Hamblin and Moorlock, 1995). These are the Kesgrave Sands and Gravels, a terraced sequence of fluvial sands and gravels corresponding to the preGlacia1 River Thames; the Bytham Sands and Gravels, a similarly terraced fluvial sequence deposited by a river flowing fiom the West Midlands to the Lowestoft area, and the Cromer Forest-Bed Formation, a coastal coqlex of interbedded fluvial, estuarine and marine strata which form the downstream correlative of the Bytham Sands and Gravels. In the memoir for the district (Arthurton et d.,1994) these are combined as the Kesgrave Group, but that practice has not been adopted elsewhere. The bmer Fomt-Bed Fodon is known along the Norfolk coast north of the present district, but in the Borehole [3834 3 1121 (West, 1980), Corton Formation rested on Pastonian strata which have been included in the Crag in the present survey, so no strata now accredited to the Cromer Forest-Bed Formation are present. The Formation is also known fiom coastal areas north and south of Lowestoft, but it is possible that these and the coastal outcrops represent separate estuaries. Either way it is unlikely to be present the Westwick district.

The earliest members of the Kesgmve San& and Gravels have commonly been portrayed as extending northwards through eastern Suffolk and Norfolk (Rose, 1994; Arthurton et d., 1994). However, mapping of the Lowestoft and Saxmundhatn 1:50 000 geological sheets has revealed no evidence of these deposits north of Aldeburgh (Hamblin and Moorlock, 1995), and it appears unlikely that the Thames ever crossed north-eastern Suffolk or Norfolk, although it may well have flowed northward beneath what is now the North Sea east of the present district. It is thus unlikely that the Kesgrave Sands and Gravels are present in the scottow district.

The Bytham San& and Wels are known to follow the line of the River Waveney in the area around Bungay, and are believed to continue north-eastward to pass into the Cromer Forest-Bed Formation between Lowestofi and Yarmouth (Hopson and Bridge, 1987). Sands and gravels with a pebble content resembling the Bytham Sands and Gravels are known at Flordon, south of Norwich (Rose, Allen et d.1996), but there is no evidence that they occur within the present district. However a third river is believed to have existed, farther north than the Kesgrave or Bytham rivers and flowing eastward from the Pennines to pass into the Cro&er Forest-Bed Formation inporth Norfolk. A pebble suite implying input fiom this 'Northern River' is recorded in the Crag at How Hill on sheet TG 31 NE (Rose, Gulamali et

17 Technical Report WA/97/77 17th September 1997 al., 1996).

Although it is considered unlikely by the present author that the Kesgrave Sands and Gravels semu stricto occur in Norfolk (Hamblin and Moorlock, 1995, 1996, Hamblin et al., 1996), sands and gravels with a pebble content implying derivation fiom the proto-Thames are common in the area (Green and McGregor, 1996). However most of these deposits are marine and hence form a part of the Crag Group. The Crag at How Hill contains proto-hes as well as Pennine material. Where fluvial deposits with a proto-Thames pebble signature occur, for instance at Caistor St. hundsouth of Norwich (Postma and Hodgson, 1987) and at Mayton Wood Pit on sheet TG 22 SW ('Coltishall' in Rose, Allen et al., 1996), they overlie Crag with a similar pebble content, and could have been derived by re-working of that.

It is thus likely that after the completion of the intilling of the marine Crag basin, the mouth of the 'Northern River' moved eastward and fluvial deposits were formed in the present district. These would be expected to contain clasts derived fiom the Pennines via the 'Northern River', and also proto-Thames material derived fiom reworking of the youngest Crag. It is thus possible that gravelly sands interpreted as Corton Formation or as Crag during the current survey might belong to such a fluvial formation. Since they are fluvial rather than marine they would be expected to have less well rounded flints than in the Crag, so in field mapping they could be mistaken on the ground for Corton Formation. However, the thickness of such a formation is not likely to be more than a few metres.

The Anglian glacial deposits of Norfolk are included within two formally defined formations (Arthurton et al. 1994), the Corton Formation below and the Lowestoft Till Formation above, although only the former is present in the Scottow district. The formations derive fiom two separate ice-sheets, the North Sea Drift or 'Scandinavian Ice Sheet' which entered the area fiom the north or east of north, and the 'British €%stern Ice Sheet' which entered fiom the west. In general it can be said that the deposits of the Corton Formation are derived fiom the former ice sheet, since they are characterised by a suite of Scandinavian igneous and metamorphic erratics, while the deposits of the Lowestoft Till Formation are derived fiom the latter ice sheet and confain erratics derived fiom Mesozoic outcrops to the north-west, principally the Chalk and heridge Clay. However, there is evidence to suggest that the deposits of the Corton Formation also include detritus fiom the British Eastern Ice Sheet.

Where the two formations are found in contact, the Lowestoft Till Formation always overlies the Corton Formation, and it has been suggested (eg Hopson and Bridge, 1987) that the Scandinavian Ice Sheet withdrew fiom East Anglia before the British Eastern Ice Sheet reached the area. However, many more authors (eg Hart and Peglar, 1990; Hart and Boulton, 1991) consider that the two ice sheets co-existed, although the Scandinavian Ice Sheet must have retreated fiom the area before the British Eastern Ice Sheet reached its eastern limit. A possible explanation is that the Anglian in reality represents two glaciations, as suggested by Sumbler (1995) on the basis of work in the South Midlands. The main Anglian glaciation is genefally ascribed to Oxygen Isoto$e Stage 12 (Bowen et d.,1986), principally because deep- sea data show this to be one of the coldest stages of the Mid-Pleistocene, and on this basis

18 Technical Rqport WA/97/77 17th September 1997 it is accepted that the Corton Formation dates fiom Stage 12. However, the type site of the Hoxnian, at Home, has been shown by amino acid geochronology to date fiom (warm) Stage 9 (Bowen et al., 1989), hence it is likely that, at least in western Suffolk, the Lowestoft Till Formation dates fiom (cold) Stage 10. If the Lowestoft Till Formation represents a single till sheet then the same age must apply in Norfolk, but this has not been proved, and in particular no (warm) Stage 11 deposits have ever been found underlying the Lowestoft Till Formation, even where it overlies the Corton Formation. The possibility thus arises that the British Eastern Ice Sheet advanced into east Anglia during both stages 12 and 10, with the Scandinavian Ice Sheet only reaching the area in Stage 12.

Corton Fonrwdion

The Corton Formation is present throughout most of the district, everywhere overlying the Crag Group. Mapping indicates that the base of the formation lies at around OD +13/18m where it overlies the Crag at outcrop in the south, and at +10/13m in boreholes TG 22 W11 and /15- 18 in North Walsham, while, as discussed above under the Crag Group, estimates can be made of the level of its base in other boreholes (Figure 6). On this basis, the formation is thickest, about 31q beneath North Walsham.

The formation comprises tills (diarnicts), sands and sandy gravels, and subsidiary lacustrine clays, and it is b to comprise both waterlain and terrestrial sediments (Lunkka, 1988; 1994). Eyles et al. (1989) noted that the close association of tills and sands indicates allied depositional environments, and considered that the tills were the products of 'rain-out' of fme- grained suspension and come debris fiom floating ice. They concluded that the water-lain deposits are marine, but Lunkka (1994) considered that they formed in a large lake. It is now widely believed that the Dover Strait was cut by the overflovv of a pro-glacial lake during the Anglian (Gibbard, 1988; Hamblin et al. 1992), and it is suggested that part of the Corton Formation was formed within this lake, held up between the Chalk ridge of the Dover Strait to the south and the 'Scandmvian Ice Sheet' to the north. The stratotype of the formation is at Corton in the Great Yarmouth district (Arthurton et al., 1994). Here a basal till, the Corton Till, is overlain by fine-grained chalky sands, the Corton Sands. The Corton Till comprises very silty sandy clay or clayey sand, commonly laminated, with a scatter of pebbles. It is brownish grey to yellowish brown in colour and firm to stiff when fiesh but in surface outcrops it is commonly decalcified and weathers rapidly to a soft and friable condition because of its high sand content. At least a part of the till is believed to be water-lain, formed by the 'rain-out' of material fiom a floating ice-sheet (Eyles et al., 1989). However, the basal part of a till exposed at the base of the Corton Formation in a temporary section at How Hill [377 1991, assumed to be laterally equivalent to the Corton Till, lacked laminations and appeared to have been formed sub-aerially (Rose, Gularnali et al., 1996). Mechanical analysis of till from an area around Lowestoft (Bridge and Hopson, 1985; Hopson, 1991) showed the Gmm fiaction to be extremely uniform and to comprise 22.0% clay;- 23.6% silt and 54.4% fme-, and medium-grained sand, while pebbles and come sand (>4mm) accounted for only 4.7gby weight and included a high percentage of come sand-

19 Technical Report WA/97/77 17th September 1997 grade chalk. Pebbles were mostly flints, with subordinate vein quartz, quartzite, chalk and shell hgments (fiom the Crag), and a sparse suite of rhomb porphyries, non-porphyritic lavas, mica schists, gneisses and granitoids believed to be of Scandinavian origin (Boswell, 1916). The 4mm to 8mm size range comprised 54% flint, 24% vein quartz, 8% quartzite, 3% sandstone and 2% each of litnestone, ironstone and ignmus/metamorphic rocks.

The Corton Sands comprise greyish or yellowish brown well sorted fine- to medium-grained sands, locally clayey, formed fiom sub-angular to sub-rounded quartz with subsidiary sand- grade flint, quartzite and disseminated chalk grains, calcite prisms and some mica flakes. Thin layers of silt, clay or pebbly diamicton occur, but pebblegrade material accounts for only 0.3% of the deposit (Hopson and Bridge, 1987), occuring as stringers of fine-grained gravel with angular and rounded flint, vein quartz, quartzite, chalk and traces of Scandinavian porphyry, granitoids and metamorphics. Sedimentary structures recorded in coast sections demonstrate that the sands are waterlain, and it is suggested that they were deposited in the ice-dammed lake, ahead of the ice-sheet fiom which the till was deposited. After the till was formed, the icssheet retreated northwards to leave open water within which the sand was deposited. Further, the high degree of sorting and roundness of the sand grains, which gives them a smoother 'feel' than the Crag sands, implies that at least a proportion of the material has an aeolian history, presumably being blown into the body of water in which the strata were forming.

Hopson and Bridge (1987), working in the Waveney Valley (Lowestoft district), identified a clastic unit of the Corton Formation below the Corton Till, which they termed the Leet Hill Sands and Gravels. At Scratby they also identified a second Corton Formation till above the Corton Sand, overlain by further sands and then a third till, although it is possible that this third till may be part of the Lovvestoft Till Formation. In the area around (Hamblin, 1997c), the Corton Formation comprised a discontinuous basal sand and gravel unit (which would equate with the Leet Hill Sands and Gravels), overlain by the Corton Till, the Corton Sands, and a firther till. The gravels within the basal unit of the formation are dominated by sub-angular to angular black-hearted white-patinated flints in a matrix of fine- to coarse-grained sand. Other pebbles include quartz and quartzite, sandstones and igneous rocks.

Mapping of the Corton Formation is hindered by the overlying cover silt, which often has a basal bed of gravel which is impenetrable to an auger, so while it has proved possible to broadly separate areas of clay deposits (mostly till), and arenamus deposits (Corton Sands, sands and gravels) it is likely that fixher pods and patches of till occur within the arenamus deposits, and vice versa. Around the margins of the district two thm, discontinuous tills crop out, and it is possible that these are the local representatives of the two Corton tills, but since they are both thin and are only around 5m apart vertically, it is more likely that they represent two leaves of the lowest Corton Till; certainly they combine into a single till in at least one area [29 261. The lower till forms the base of the Corton Formation at Skeyton [25 251, but elsewhere it is more commonly underlain by further arenmus strata comprising both fine- grained Corton Sand and coarse-grained sands and gravels. A similar mixture of fine- and coarse-grained sands occur betwey the tills and immediately above the upper till in the south of the district and at lower levels m the east and west of the district, but on the higher ground

20 Technical Report WA/97/77 17th September 1997 which forms most of the centre and north of the district, medium- to coarse-grained rather gravelly sands form a thick sdwof outwash material.

Corton Fornation - Details

North-west of Skeyton Beck, both finegrained and medium- to coarsegrained sands have been widely augered. Two patches of till have been mapped at around 27m OD [255 296, 251 2931; the northern one is believed to continue northwards onto sheet TG 23 SE and may connect with that at Tmgate Farm [270 2991, while a pond [2515 2877 at Lodge Farm may indicate a further patch at a slightly lower level. All four patches would be of the higher of the two discontinuous tills known in the district. East of Skeyton Brook, Bryant's Heath has been extensively quarried for sand. This is orange, medium- to come-grained, and moderately gravelly, with angular flint pebbles. Similar sands have been augered as far east as the outskirts of North Walsham, with patches of till [270 299,268 2931 within the sands at about +33m OD.

Boreholes TG 22 NE/5 and 6 [2592 2908, 2614 29031 record sand to 10.7m depth, resting on thick clays which are believed to include both the Corton Formation lower till and the highest Crag. Southwards and eastwards from here, uniform medium- to coarse-grained slightly gravelly sands crop out over a large area, at levels from over +4Om OD down to the Skeyton Brook in the west at +15m OD, with fme-grained Corton Sand only rarely augered [2515 2766,2538 2768,2646 27791. These sands yield very dry, poor arable soils, and large areas of woodland extend fiom Oak Hill [254 2881 to Dairy Farm [280 2681. Borehole TG 22 W7[2584 27891 penetrated yellow sand to 7.6~sandy day to 12.8~and brown sand to 20.7~the clay is relatively thick and may represent both the local tills joined together. Boreholes /29-30 [2616 27861 nearby record only grey and brown sand in the Corton Formation. A pit [2740 2757 beside Perch Lake, dug to bury burned tree stumps, revealed the following section: Head, gravelly sand... 0.5m Corton Formation; sand, bd, medium-grained, well bedded, cment bedding dipping due NE, few pebbly stringers ... 1.Om+ South of North Walsham, the fields to the west of Norwich Road are covered with a gravel wash, but brown medium-grained sand was augered locally and was seen at a badger sett E2759 28181 adjacent to an infilled sand pit [2762 28241. Boreholes TG 22 W15-18 [278 2911 record sands and gravels down to 15.2-17.4111, till to 22.9-27.7~sand to 28.9- 30.5111, till to 30.6-32.2~then more sand and gravel down to 33.7m in /17, although the lower till rests directly on Crag in /15 and /18. Borehole /1 [2785 28341 records sand and gravel to 18.3m then "mixed sand clay stone" to 24.4m: this may include two tills. Between the Norwich Road, the railway and the woods at Postle's Corner [283 2751, the land forms a flat plateau. Mostly medium-grained sand was augered, with locally come-grained sand or gravel, which may be wash. Fine-grained sand was only augered in the south [2863 2778, 2877 27791. Augering around Piper's Pit [2828 28281 failed to reveal any clays, so possibly this large pond was dug for watering cattle and has been puddled. Borehole TG 22 W11 [282 2941 records sand and gravelio 18.w sandy clay to 22.3m then brown sand to 29.0%

21 Technical Reprt WA/97/77 17th September 1997 13 [2816 29311 records sand and gravel to 22.9m then clay to 28.3~and /14 [2840 28001 records sands and gravels to 22.9m then "soft brown clay and stone" to 24.4~so in all cases only one till is present.

East of the railway, augering the plateau north-west of Field Lane revealed gravels and medium-grained sands. East of North Walsham the ground slopes steeply down to the east, and both fine- and medium-grained sands were augered on the slopes. There are several abandoned sand pits E292 299,293 295,295 297,297 2991. Between Field Lane and the new Yarmouth Road the Corton Formation outcrop slopes very steeply down to the east. More fine- than medium-grained sands were augered, although a wash of gravel obscures these above Holgate Poultry Farm [300 2861. Four large disused sand pits are known: the one [290 287 near Cangate Lodge has been planted and turned into a caravan site, two [294 290, 295 2791 have been completely infilled and that [295 2881 south of Hagg Farm has been largely so. The following section was seen in the south-west face of this pit [2946 28731: Sand, buffwith orange beds, medium-grain&, mainly flat bedded, some gentle cross-bedding; scattered pebbles, mainly flint, up to 4 cm in length in discrete beds... c 4.om

A thin bed of till runs fiom [295 2901 near Hagg Farm to [298 2951 beyond Happisburgh Road, at around +20m OD, but augering demonstrated that it does not extend farther. Borehole TG 22 W4[2945 27861 records sand and gravel to 17.7m depth, +18m OD, then grey sand with clay to 27.4m: it is possible that the till is included in the latter unit. Boreholes TG 22 W20 and /28 [2985 2804, 2998 28551 record loam, sand and shingle to depths of 8.3m and 5.5~+9m and +8m OD: these start below the level of the till on the hillside, and do not indicate a lower till. Between the new Yarmouth Road and the railway, medum-grained sands were augered on the plateau, and fine-grained sands below the rim [2960 2780,299 2761.

In the south-west of the district, mainly medium-grained sands were proved on the plateau west of Malthouse Common [271 2711 and north of Youngman's Lane [264 2611, with scattered instances of gravel and fine-grained sand. There are a number of abandoned sand pits, both concentrated at Swanton Hill Common [262 266,265 267 and scattered elsewhere [257 272,258 272,260 272,268 273,262 2681. The slopes to the east, south and south-west include thick beds of fine-grained as well as medium-grained sand, but the slopes to the west past Skeyton Corner [253 2741 and High View [252 2661 are formed of uniform medium- grained sand, very loose and subject to strong wind deflation on this exposed, west-fming slope. Two seams of till were detected, a lower one [250 2741 at +15m OD near Nixon Farm, and a higher one at +23m to +26m [250 267,250 263 to 260 2601. Augering failed to reveal any till around the pond [2550 27201 at +28m OD at Manor Farm, so possibly this was dug as a duck pond and has been puddled. Borehole 42 [2516 26631 records brown clay (the upper till) to 4.6m then sand to 10.7~+15 OD. Below this is "blue clay" which is most likely Crag, but it is posssible that it includes the lower till at the local base of the Corton Formation. Borehole TG 22 W2[2644 27301 records sand and gravel to 9.1~brown clay to 2234 then grey sand the thic$ clay may represent both tills combined. No till is present on the slopes east of Swanton Abbott, between Swanton Hill Common and Long Common

22 Technical Report WA/97/77 17th September 1997 Lane, but a till occurs at the base of the formation [256 257 to 251 2501 at Skeyton, which correlates with that at Nixon Farm. A small outlier of the lowermost Corton Formation gravelly sand occurs [269 2541 straddling Aylsham Road, borehole TG 22 NFd26 [2700 25381 records "sand and clay" to 1.2m dep~although the soils indicate gravel.

In the south-east quarter of the district; medium-graind sands dominate north of Westwick House [286 2631 and fine-grained sands to the south. There is very little gravel wash over the slopes even though patches of sand and gravel of uncertain age and origin are mapped [276 260,277 258,284 2561. The following section was measured in an abandoned sand pit [2954 27461 beside Bunn's Hill Wood:

Sand, buff, some darker orange staining; fine- to coarsegrained, mostly medium-graind, pebbly stringers, pebbles to 8cm long mostly shattered angular flint also quartz and quartzite; horizontal, well bedded, mostly planar bedded, some shallow and steep angled cross-bedding dipping to the south-west ... c 5.0

Below this pit, a thin till crops out at about +20m OD on the hillside [300 274 to 300 2661: this can probably be correlated with that which crops out at a similar height farther north. A lower till [297 2691 crops out at Bunn's Farm. Extending eastwards fiom Westwick Park, two thin leaves of till [288 262,284 2601, which are both underlain and overlain by fine-grained sands, merge into a single till 17292 261 to 298 2611; this may correlate with the two immediately to the north. A single till, underlain and overlain by fine-grained sands, crops out either side of the hill south of Westwick Park [292 257 to 286 250,285 250 to 282 2551. To the south-east, a lower till crops out [295 250 to 298 2521 at the fiozen food fxtory, but borehole TG 22 NE/23 [2966 25391 does not record this, only sands and gravels to 10.7m depth (these will include Crag as well as Corton Formation). Farther west, a till [282 253 to 276 2551 locally forms the base of the formation [277 2511, and two smaller seams of till farther north [274 260, 276 261 to 276 2671 may be correlated with it, but two smaller patches beside the Norwich Road [280 259, 278 2601 lie at a rather higher level.

This deposit is characterised by sandy gravels dominated by angular shattered flints up to about 20 cm long, with minor rounded flint, quartz, quartzite and sandstone, in a matrix of coarse-grained sand. It occurs on hilltops, invariably overlying gravelly sands high in the Corton Formation. Five patches occur in the north-east quarter of the district [293 292, 292 286,293 288,294 288,295 2861, at between +30m and +40m OD, and three patches in the south-east [276 260,277 258,284 2561 at levels of +26m to +32m OD.

Since the deposit occurs only at high levels, unrelated to the post-glacial drainage, it is unlikely that it represents deposition later than Anglian, but it is not clear whether it belongs to the Corton Formation or the Lowestoft Till Formation. The high content of relatively large, shattered flints would suggest the latter, since high concentrations of large flints are uncofiimon high in the Corton Fonlpation, but this cannot be satisfactorily demonstrakd since no undoubted Lowestoft Till Formation is known in the immediate vicinity. Alternatively the

23 Technical Report WA/97/77 17th September 1997 deposit may have been formed by winnowing of the Corton Formation, with concentration of the larger flints by removal of the finer constituents.

During the Wolstonian/Saalian and hensian/Weichselian glacial episodes, southern England was subject to periglacial conditions, and sea levels in the North Sea dropped sharply as up to 5% of the global water budget was locked up in the form of ice. During these periods remarkably little erosion occurred in the present district: the bulk of the erosion of the Corton Formation must have occmed during the Anglian stage, since in adjacent districts the Lowestoft Till Formation occurs at low levels in river valleys. Hence later erosion must be very largely restricted to overdeepening of the river valleys.

Four deposits were formed during these periods: the Yare Valley Formation, cover silt, gravelly head, and head. The Yat~Valley Formadion (Arthurton et al., 1994) occm in the valleys of the River Bure and some of its tributaries. It comprises fine to coarsegrained gravels, mostly of flint, with variable mounts of fine to coarsegrained sand, some silt, shell fiagments and chalk cobbles. It is up to 1lm thick near Great Yarmouth, and is generally considered to be of late Devensian andor early Holocene age. Similar gravels are likely to have been formed late in the Angliq as the North Sea Ice Sheet waned and the post-glacial drainage system was initiatd but these would most probably have been eroded and reworked during Wolstonian and Devensian periods of low sea level, so the surviving deposits are assumed to be Devensian. Boreholes beside the River Bure in Horstead, at the northern end of sheet TG 21 NE,revealed up to 10.5m of andar flint gravel, fine to coarsegrained sands and silts. In the present distri& the Yare Valley Formation has not been proved by boreholes, but it may be assumed to be present beneath the peat and alluvium of Skeyton Beck Stakebridge Beck and Westwick Beck, up to about 2.0m thick.

Cover silt is the term given to a drape of silt and sand which locally masks the outcrop of the Corton Formation. Silt is the main component, with subordinate fine to medium-grained sand, giving a bimodal distribution (Catt et al., 1971; Perrin et al., 1974). These authors consider the deposit to be aeolian in origin, possibly modified by frost-heaving and biological mixing. It is considered to be Devensian in age, formed during the last ten thousand years which preceded the Flandrian marine transgression, and derived by aeolian transport fiom Devensian outwash sediments in northern England. In the present district the cover silt is not shown on the map. It may be up to around 1.5m thick, but most commonly 0.4-0.7~and tends to be thickest where it collects within concave slopes.

At the base of the cover silt, where it rests upon till or gravelly sands of the Corton Formation, there is a layer a few centimetres thick of hard-packed gravel. "his is commonly impenetrable by hand auger, and makes mapping the underlying Corton Formation difficult. It is believed to be a deflationary product of the underlying units, the fines having been winn6wed out by the wind to leavp hard-packed gravel. There is commonly no such gravel where the cover silt rests upon gravel-fiee sands of the Corton Formation.

24 Technical Report WA/97/77 17th Septmber 1997 l3ead comprises poorly sorted and poorly stratified clayey and gravelly sands and sandy clays derived fiom earlier Quaternary deposits by mass movement on sloping ground. The processes involved include hillwash and soil creep as well as solifluction. The head is assumed to be largely late Devensian in age in view of the periglacial conditions then prevailing, but some may survive fiom the Wolstonian or even late Anglian, and some hillwash and soil creep may date fiom the Holocene. Remarkably little head is seen in East Anglia considering the intensity of the periglacial climate to which the area has been subjected during the last three glaciations, and in the present district head sufficiently thick to show on the map is restricted to small strips and patches up to about 2.bthick in the stream valleys. A strip of head up to 150m wide is ubiquitous at the base of the valley of the Skeyton Beck and its tributaries in the north-west of the district. Strips up to 300m wide occur at Skeyton [25 251 and along Stakebridge Beck east of its junction with Westwick Beck [267 2511; the latter extends eastwards as a much thinner strip which continues across the watershed to Worstead on sheet TG 32 NW. Rather less head occurs as discontinuous patches along the valley of Westwick Beck [269 255 to 274 2801.

ALauTvLuMANDPEAT

Alluvium comprises soft laminated silty clays and clayey silts, deposited by streams during the Holocene. It is strongly developed in the valley of Westwick Beck [267 253 to 273 2711, and is also recorded in the valleys of Stakebridge Beck [258 2501 and Skeyton Beck [250 279 to 252 2861. It is believed to range up to 2.h thick in the present district.

Peat is widespread only in the valley of Stakebridge Beck [258 251 to 267 2521, up to about 2m thick.

The peat and alluvium of the present district are not included in the Breydon Formation (Arthurton et d.,1994) since that formation is defined as a 'fossil' formation formed under estuarine to marine conditions, and is not intended to include any fluvial deposits formed so far inland as to be out of estuarine influence. It is unlikely that marine influences persisted this far upstream.

25 Technical Report WA/97/77 17th September 1997

There is little made ground in the district. This is largely restricted to railway and road embankments, the dams of omenta1 lakes, and the infill of disused sand pits east and south-east of North Walsham. There may be Mer,unknown areas of infilled ground (wholly back-filled worked ground) which are not shown on the map. Two areas of landfill south of the new Yarmouth Road [292 280,293 2791 do not infill old pits and may be at least in part constructed fiom sand excavated fiom the farm yard lorry park [291 2831 at Carlton Farrr~ The big disused sand pit [295 2791 at Sandhill Farm has been infilled with domestic refuse. It is not clear whether the similar domestic refuse landfill site [294 2901 at Hagg Farm is infilling an old sand pit or a natural valley, or both.

There are a few small disused pits within the Crag. They may have worked any combination of gravel, clay and sand. The sands of the Corton Formation have been widely worked. Pits on common land at Bryant's Heath [258 2931 and Swanton Hill Common [265 2671 will have had a long history of working, none have been infilled but all are now overgrown. A number of large pits east and south-east of North Walsham are of more recent origin, but again all are now abandoned: one 17290 2871 is now a caravan park and many have been used for the disposal of domestic refuse. Other smaller sand pits are scattered throughout the outcrop, generally at lower levels to the west, south and east of the main North Walsham plateau. Some of the disused pits shown within the outcrop of arenaceous Corton Formation may have been within small 'pods' of till, eg flow tills. There are no undoubted brick clay pits within the mapped outcrop of the Corton Formation tills, possibly because all the bodies of till are thin and interbedded with sands and gravels. All the holes within the till outcrops are small and were probably dug as ponds for watering cattle. Two ponds within the mapped outcrop of arenaceous Corton Formation [282 282, 254 2721 have presumably been puddled, as duckponds or as ponds for watering cattle. There are no peat workings or 'Broads' known in the district, but some small ponds within the peat or alluvium were probably dug as wildfovvl decoys.

26 Technical Report WA/97/77 17th September 1997 EGoNoNIIcGEoLxx;r7rl

At present mineral extraction activity within the district is restricted to minimal sand extraction by farmers for there own use, although in the past, large quantities of san4 and probably some brick clay and gravel, have been won fiom the Crag and Corton Formation. Further extraction of sand fiom the Corton Formation is possible. Gravels within the Crag are of high quality, comprising largely flint, quartz and quartzite, but they are much thinner in the present district than in the Bure Valley to the south and hture workings would appear unlikely. Further gravels occur both in the Corton Formation and in the Yare Valley Formation: the former are too sandy and possibly too poorly sorted to be of economic value, while the latter have not been explored but would possibly be too thin and too diEcult to extract to be economic.

Water supply The Crag, the sand and gravel units of the Corton Formation, and any intervening pre-Anglian drift deposits are minor aquifers, with water flow through pores between the sand grains. The Crag is in hydraulic continuity with the basal sand and gravel unit of the Corton Formation, and with any intervening pre-Anglian drift deposits. The tills in the Corton Formation are thm, sandy and discontinuous, and would not be effective aquicludes. The Upper Chalk is a major aquifer, with all flow through fissures rather than intergranular, and the Crag and Upper Chalk are in hydraulic continuity.

Within the district, 30 bores for water are known, TG 22 NE/1 to 30, and depths quoted range fiom 30.5m to 137.1m All of these penetrated the Upper Cwbut detailed logs for some are not known. Where logs are available, the depth of penetration into the Upper Chalk is shown in Figure 4. Wells revealed rest water levels of +8m to +27m OD. Water consumptions quoted vary widely: a %hour pumping test at TG 22 NEY5 at 1400 gallons (6364 litres) per hour yielded a depression of 6m, with recovery in 75 minutes, while TG 22 NEY23-24 have yielded 250 000 gallons (1 136 491 1) per day maximum. Water fiom the Upper Chalk is hard, and some well logs reported it to be fmginous.

27 Technical Report WA/97/77 17th September 1997

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Bowen, D Q Hughes, S, Sykes, G A, and Miller, G H. 1989. Land-sea correlations in the Pleistocene based on isoleucine epirnerization in non-marine molluscs. Ndm, 340, 49-5 1,

-----,Rose, J, and McCabe, A M. 1986. Correlation of Quaternary glaciations in England, Ireland, Scotland and Wales. @atemmy Science Reviews, 5, 299-340.

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Cmeron, T D J, Crosby, A, Balson, P S, Jeffery, D €3, Lott, G K, Bulat, J, and Harrison, D J. 1992. offshore regional ~prt:the geology of the southem North Sea (London: HMSO for the British Geological Survey).

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Cox, F C, Gallois, R W, and Wood, C J. 1989. Geology of the country around Norwich. Memoir of the British Geological Szavey, Sheet 161 (England and Wales). Eyles, N, Eyles, C H, and McCabe, A M. 1989. Sedimentation in an icecontact subaqueous setting: the mid-Pleistocene 'North Sea Drifts' of Norfolk, UK. @atemmy Science Reviews, 8, 57-74.

Funnell, B n/l, Norton, P E P, and West, R G. 1979. The Crag at Brmerton, near Norwich, Norfolk. Philosophical Tmmtions of the Royal Society of London, Series B, 287,489-534.

Gallois, R W, and Morter, A A. 1976. Tmch Borehole, (132) Sheet. In: IGS Boreholes 1975. Reprt of the Institute of Geological Sciences, No.76/10. Gibbard, P L. 1988. The history of the great northwest Ewopean rivers during the past three million years. Philosophical Trimtions of the Royal Society of London, Series B, 318, 559-602.

Green, C P, and McGregor, D F M. 1996. The Kesgrave and Bytham Sands and Gravels of East& Suffolk: a lithostratigrapqcal comment. @atemmy Newsletter, 79, 3-7.

28 Technical Report WA/97/77 17th September 1997 Hamblin, R J 0. 1997a. Geological notes and local details for 1 : 10 000 sheet TG 22 SE (Scottow). British Geological Survey Technical Report WAl97125. ----- 1997b. Geological notes and local details for 1 : 10 000 sheet TG 21 NE (Belaugh). British Geological Survey Technical Report WAl97124.

----- 1997c. Geological notes and local details for 1 : 10 000 sheet TG 41 NW (Potter Heigham). British Geological Survey Technical Report WAl95112. ----- Crosby, A, Balson, P S, Jones, S M, Chadwick, R A, Penn, I M, and Arthur, M J. 1992. Uniied Kingdom offshore ~giod~prt: the geology of the English Chl.(London: HMSO for the British Geological Survey). ----- and Moorlock, B S P. 1995. The Kesgrave and Bytham Sands and Gravels of Eastern Suffolk Qiwtematy Newsletter, 77, 17-3 1. ----- and -----.1996. The Kesgrave and Byulam Sands and Gravels of East Anglia. A reply to J. Rose, P. Allen, C.P. Green, RW. Hey, S.G. Ms,J.M. Sinclair, and C.A. Whiteman. Qiwtenmy Newsletter, 79, 26-34.

9 ----- , Booth, S J, Jeffkry, D 6 and Morigi, AN. 1997. The Red and Norwich Crag Formations in eastern Suffolk. hceedings of the Geologists' Association, 108, 11-23. ------9 , and Rose, J. 1996. The Kesgrave and Bytham Sands and Gravels of Eastern Suffolk, reply to a lithostratigraphical comment by C.P. Green and D.F.M McGregor. Qiwtematy Nzwsletter, 79, 8-9. Hart, J K, and Boulton, G S. 1991. The glacial drifts of northeastern Norfolk. Ln: Glacial deposits in Gzd Britain and Izld Ehlers, J, Gibbard, P L, and Rose, J (editors). Rotterh: Balkem

----- and Peglar, S M. 1990. Further evidence for the timing of the Middle Pleistocene Glaciation in Britain. hceedings of the Geologists' Association, 101, 187-196.

Hopson, P M. 1991. Geology of the Beccles and Burgh St.Peter district. British Geological Survey Technical Report WAl91153. ----- and Bridge, D McC. 1987. Middle Pleistocene stratigaphy in the lower Waveney valley, East Anglia. hceedings of the Geologists' Association, 98, 171-185.

LwJ P. 1988. Sedimentation and deformation of the North Sea Drift Formation in the Happisburgh area, North Norfolk. 109-122 in: Glaciotectonics: Fomzs dhcesses. Croot, D (editor). (Rotterdam, Balkema).

29 Technical Report WA/97/77 17th September 1997 ----- 1994. Sedimentation and lithostratigaphy of the North Sea Drift and Lowestoft Till formations in the coastal cliffs of northeast Norfolk, England. Jodof wemayScience, 9, 209-233.

Moorlock, B S P, Hamblin, R J 0, Booth, S J, and Morigi, A N. In p~ss.Geology of the country around Lowestoft and Saxmundhm. Memoir of the British Geologicd Survey, sheets 176 and 191 (England and Wales).

Peake, N B, and Hancock, J M 1961. The Upper Cretaceous of Norfolk. Tmmtiomof the Nofolk and Norwich Nddists' Society, 19, 293-339. Reprinted with addenda in 1970: 293-3395 in: The Geology of Nofolk. Larwood, G P, and Funnell, B M (editors). London and Ashford Geological Society of Norfolk.

Perrin, R M S, Davies, E& and Fysch, M D. 1974. Distribution of late Pleistocene aeolian deposits in eastern and southern England. Ndm, 248,320-324.

Postma, G, and Hodgson, GE. 1987. Caistor St.Edmund Pit (TG 240 04). 131-139 in: Pliocene-Midle Pleistocene of htAnglia Field Guide. Gibbard, P L, and Zalasiewicz, J A (editors). Cambridge: Quaternary Research Association.

Reid, C. 1882. The geology of the country around Cromer. Memoir of the Geologicd Survey, England and Wdes.

Rose, J. 1994. Major river systems of central and southern Britah during the Early and Middle Pleistocene. TernNov~ 6, 435-443.

-----,Allen, P, Green, C P, Hey, R W, Lewis, S G, Sinclair, J and Whiteman, C A. 1996. The Kesgave and Bytham Sands and Gravels of East Anglia. Quatemmy Nmsletter, 79, 10- 25.

-----,Gulamali, N, Moorlock, B S P, Hamblin, R J 0, Jefiey D E& Anderson, E, and Lee J A. 1996. Pre-glacial Quaternary sediments, How Hill near , Norfolk, England. Bulletin of the Geologicd Society of Nofolk, 42, 3-28.

Sumbler, M G. 1995. The terraces of the rivers Thame and Thames and their bearing on the chronology of glaciations in central and eastern England. hceedings of the Geologists' Association, 106, 93-106.

West, R G. 1980. The pre-gmid Pleistocene of the Nofolk and Sgfolk coasts. Cambridge: University Press.

Wood, C J. 1988. The stratigraphy of the Chalk of Norwich. Bulletin of the Geologicd Society of Nofolk, 38, 3-120.

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Technical Report WA/97/77 17th September 1997 APPETWIX - ABBREVIATED LCES OF SEI;dijclrlQ) BOREHOLES HELD BY BGS 20SEPlXMl3ER 1997

Confidential boreholes are omitted, also boreholes for which no geological logs are held. The stratigraphic classification given is the author's interpretation of the drillers' log; the quality of data is such that this must be treated with caution. Copies of the original logs may be obtained fiom the Survey's offices at Keyworth, the site numbers given here are prefmed TG 22 NE.

Depth O.D. (m) Level (m) 1. Tollgate Fann, No& Walsham E2785 28341. OD c +35. Top soil 0.6 Colton Fodon, Clag Gmup Sand 9.1 +26 Gravel 9.4 +26 Sand stone 18.3 +17 Mixed sand clay stone 24.4 +ll (possible base of Corton Formation) Yellow sand 33.5 +1 Mixed sand clay stone 42.7 -8 Upperchalk Brown sand chalk 44.2 -9 Gravel 44.5 -10 Mixed hard chak, softer chalk 106.7 -72

2. Bmke Fann, SwhnAbbote [2644 27301. OD c +39. Top soil 0.3 Colton Fodon, Chg Gmup Loam 0.9 +38 Brown Sand 5.5 +33 Sand & stones 9.1 +30 Brown clay 22.9 +16 Grey sand 29.9 +9 Grey sand & clay 32.9 +6 Grey sand & shells 35.1 +4 Upperchalk Chalk 76.2 -37

31 Technical Report WA/97/77 17th September 1997 3. EB. hGce (Roses) LM, North W&ham [2816 29311. OD c +40 Corton Formalion, Crag Gmup Loam 0.9 +39 Sand and stones 14.6 +25 Brown sand 22.9 +17 Brown clay 28.3 +12 (possible base of Corton Formation) Grey sand 30.8 +9 Grey clay 33.8 +6 Greensand 38.7 +1 Sea shells 39.0 +1 Grey sand and stones 41.5 -2 Upper Chalk Chalk 68.6 -29

4. Sandy Hill, Wolstead [2945 27861. OD c +36 Topsoil 0.3 Corton Formalion, Crag Gmup Sand and stones 0.6 +35 Sand 5.5 +3 1 Sand and stones 8.2 +28 Sand 17.7 +18 Grey sand with clay 27.4 +9 (possible base of Corton Formation) Grey sand and stones 32.3 +4 Grey sand 38.4 -2 Sand and shells 39.3 -3 Stones 40.2 -4 Upper Chalk Chalk, Chalk, hard, with flints 61.0 -25 5. Heath Famq Skyton Road [2592 29081. OD c +23 Top soil 0.3 Corton Formaution, Crag &up Sand 10.7 +12 Clay 16.8 +6 Sand 25.6 -3 upper- Chalk 57.9 -35

a

32 Technical Report WA/97/77 17th September 1997 6. Bridge Farm Ihowe, Skeyton Road [2614 29031. OD c +26 Top soil 0.6 Colton Forimlion, Crag -up Sand 10.7 +15 Clay 18.9 +7 Sand 28.7 -3 U@erChalk Chalk 54.9 -29

7. Skeyton [25842789]. ODc+36 Top soil 0.3 Colton Forimlion, Crag &up Yellow sand 7.6 +28 Sandy clay 12.8 +23 Brown sand 20.7 +15 (possible base of Corton Formation) Grey sand 29.3 +7 Dark grey sand 36.0 OD Upper Chalk Chalk with flints 57.9 -22 8. swanton Abbott [255 2581. OD c +14 Topsoil 0.3 Crag -up Yellow clay 2.1 +12 Brown fine-grained sand 8.8 +5 Grey fine-grained sand 11.6 +2 UpperChalk Mar1 15.5 -2 Large flintdchalk 18.0 -4 Loose chalk 32.0 -18 CWflhtS 73.2 -59 11. NotfolkGanneries I& ?or& Wdsham [282 2941. OD +41 Co&n Formation Sand and gravel 14.0 +27 Sand 18.0 +23 Sandy clay 22.3 +19 Brown sand 29.0 +12 --up Running sand 29.6 +11 Sand and gravel 41.1 OD UpperChalk Mar1 and flints 42.4 -1 +Chalk and flints 121.9 -81 a;

33 Technical Report WA/97/77 17th September 1997 12. Beech Fann, Skeyton [2516 26631. OD c +26 Colton Fodon, Grag &up Brown clay 4.6 +21 Sand 10.7 +15 (possible base of Corton Formation) Blue clay 19.8 4-6 Black sand 33.5 -8 Upperchalk Chalk 44.5 -19

13. Nolth Walsham Wood Hime [2572 28361. OD c +29 Colton Formation, Grag &up San& dug well to 6.7m 12.2 +17 "hard grey gault" 18.3 +11 Not seen Not known UpperChalk Not seen c 53.3 c -24

14. fheath Fann, No& Walsham [2840 28001. OD c +37 Top soil 0.3 Colton Fodon, Cmg Group Clay, sand and gravel 3.O +34 Coarse-grained green sand 9.1 +28 Fine-grained yellow sand 22.9 +14 Soft brown clay & sand 24.4 +13 (possible base of Corton Formation) Soft grey clay & stone 25.9 +11 Hard grey clay & stone 27.4 +10 Grey sand & gravel 29.0 +8 Soft grey clay & sand 38.1 -1 UpperChalk Clay & chalk 39.6 -3 Soft chalk & flints 106.7 -70 15. NO& Walsham Water Workr 16278 2911. OD +43.6 Soil 0.3 Colton Formation Rich reddish yellow gravel and sand 2.0 +42 Flint gravel, flints up to 51cm long 2.4 41 Pale buffvery fine-grained sand 9.1 +35 Reddish brown sand 10.7 +33 Buff sand 11.6 +32 Fine-grained gravel sand 11.7 +32 Pale buff very fine-grained sand 14.6 +29 -Pale yellow loamy sand '1 15.7 +28 Reddish brown loam 21.8 +22

34 Technical Report WA/97/77 17th September 1997 Bluish compact hard stiff loamy clay, impervious to water 22.7 +21 Yellowish loam with thin bands of iron stone 22.9 +21 Yellow loamy sand 24.4 +19 Dark grey very compact san4 dark brownish grey sand 29.4 +14 Dark bluish grey stiff compact loamy clay with small stones 30.6 +13 -&UP Rounded grey flints, 2-5 cm in diameter 32.5 +11 Grey blowing sand 37.3 3-6 Pale grey stiff compact marl, impervious to water 37.5 3-6 Grey running sand, with fiagments of shells above 39.5rn depth 42.7 +1 Large flints 43.0 OD Upper Chalk Chlk 76.2 -33

17. North Walsham Water WO& [278 2911 OD +43.6 Soil 0.6 Corton Formation Loamy sand 1.5 +42 Flint gravel with red sand 3.7 +40 Very fmegrained pale buff sand, water bearing below 12.8rn 17.4 +26 Light clay, with a mixture of red loam and fine-grained sand 27.1 +17 Blue clay, stiff and compact 27.7 +16 Fine-grained grey sand and loam 28.9 +15 Dark grey clay, with small flint hgments 29.7 +14 Small rounded flints 32.0 +12 Grey stiff clay 32.2 +11 Fine-grained grey sand with flint fiagments 33.7 +10 WGrpup Fine-gramed grey sand, water-bearing 39.0 +5 Very fmegrained grey sand with shell hgments 39.6 +4 Close-grained stiff grey clay with fine-grained sand 41.1 +3 Large flints 41.5 +2 UpperChalk Chalk 137.1 -84

18. North Walsham Water Workr [278 2911. OD c +43 Soil 0.5 Corton Foimation Red sand 2.7 +40 Pale red sand & flint gravel 4.6 +38 Buff sand & flint gravel 6.7 +37 Brown sand & a little shingle 7.3 +36 Pale brown coarse-grained sand & shingle 8.8 +34 Buff coarse-grained sand 10.1 +33

-Fine-grained brown sand ~ 15.2 +28 Reddish brown sandy clay 17.1 +26

35 Technical Report WA/97/77 17th September 1997 Hard bluish stiff compact clay 22.6 +20 Yellow loam 23.8 +19 Yellow loamy sand 26.2 +17 Fine-grained grey sand, very compact 30.5 +12 Dark blue-grey stiff compact loamy clay with small stones 31.7 +11 cw-q Grey flints 33.5 +9 Grey sand & shell fragments 37.2 4-6 Peat 37.5 4-6 Grey sand 39.6 +3 Grey mar1 39.9 +3 Grey sand 42.3 +1 Flints 42.4 +1 Upper Chalk Dirty chalk & flints, water 48.8 -6 White chalk & flint 121.9 -79

20. Hill Farm, Worstead E2985 28041. OD +17.7 Top soil 0.6 Carton Fodon, Ckag &up Loam 5.2 +13 Sand 8.3 +9 (possible base of Corton Formation) Shingle 9.8 +8 Black sand 19.8 -2 UpperChalk Chalk 36.6 -19

21. Swanton &boU Hdl [25512560]. OD +14.3 Brick shaft 4.3 -1-10 crag -q Sand and stone 9.8 +5 UpperChalk NIarl 22.3 -8 Chalk 39.6 -25

22. Bmok Farm, Watwick [27112552]. OD +14.6 Top soil 0.3 *-up Brown sand 4.0 +11 Brown clay 4.6 +10 Brown sand 7.9 +7 Shingle 15.5 -1 upper- .-Chalk 35.1 -2 1 a

36 Technical Report WA/97/77 17th September 1997 23. Wescwick Wsted Pmducts Factory [2966 25391. OD +15.5 Corton Fomation, Crag Gmup Pale yellow sand 0.4 +15 Buff sand 2.2 +13 Coarse gravel and sand 10.7 +5 Dark reddish brown loam, slightly mottled 12.3 +3 Dark grey very compact sand 12.5 +3 Dark blue clay with small stones, impervious 22.3 -7 Grey flints 23.5 -8 Grey running sand 25.1 -10 Flints 25.3 -10 upper- Chalk 65.2 -50

26. We Cottage, Swanton Abbott [2700 25381. OD 1-12.5 Black soil 0.6 +12 Colton Formation Sand and clay 1.2 +11 -&UP Yellow sand; also shingle below 4.4 4.9 +8 Shingle 5.8 +7 'Marle' 6.1 +6 Blue clay 7.0 4-6 Grey sand and sea shells 9.1 +3 upper- Very soft chalk to 32.9; hard chalk 45.7 -33

27. 'Ihe hlly Farmers Public House [2670 25251. OD +12.1 Existing well 3.O +9 --UP Sand and shingle layers 11.6 +1 upper- chalk with flints 44.2 -32 28. Holgate Famq No& Wdsham [2998 28551. OD + c13 Top soil 0.9 +12 Corton Fomtion, Crag Gmq Sand and shingle 5.5 +8 (possible base of Corton Formation) Blue clay 6.4 +7 Running sand and shells 14.9 -2 Upper(3halk Chalk & flints 30.5 -18

37 Technical Report WA/97/77 17th September 1997 29,30. Skeyton Road, No& Wdsham [2616 27861. OD c +41 Corton Fomaiion, Crag &up Brown sand 22.9 +18 Grey sand,; below 34.1, with stones 37.8 +3 Grey sand with sea shells 40.2 +1 Upper Chalk Chalk 57.9 -7

F

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